2D vellum Simulation

[lucaspedrajas]

Hello guys , I cant find an attribute or something in vellum  to make it avoid movement in one particular angle or i'm missing it.

 

 I want to simulate a spring in a 2d domain I only want to run the simulation in Z and X   and avoid movement in Y axis 

Iwant to prevent this from happening:

Is it possible ? thank you all in advance for your help!!

[ryew]

Why not just place box-shaped colliders on either side of the spring geometry to restrict its movement?

[3dome]

I'd use a popwrangle and set v@force.y = 0; and just in case aswell v@v.y = 0;

if it doesn't work, you might want to dive into the solver and do that stuff at the right position

Edited May 4, 2019 by 3dome

[KarlRichter]

If you use a sop solver to explicitly set the y point values of the cloth geo and an additional sop solver to do the same to the constraint geo, you can very effectively constrain your sim to just two axis. See attached for example.

BTW, it may seem that you only need to manipulate the "Geometry" data, and in the simple attached demo that seems to work fine, however I have found that with complex vellum sims you really need to run over the "ConstraintGeometry" data as well.

 

vallum_x_constraint.hip

[Atom]

Thanks for the setup, Karl, that works. After taking a look at your VOP network I managed to reduce it to a single line of VEX code.

v@P = set(@rest.x,@P.y, @P.z);

So you could swap the constraint to any axis, by shuffling the values.

[lucaspedrajas]

woow amazing !! sorry for repply one week later ,  but yeah! thak you guys for the enlightening !!! you're awesome!   

[UncleBob]

On 5/6/2019 at 7:41 PM, KarlRichter said:

If you use a sop solver to explicitly set the y point values of the cloth geo and an additional sop solver to do the same to the constraint geo, you can very effectively constrain your sim to just two axis. See attached for example.

BTW, it may seem that you only need to manipulate the "Geometry" data, and in the simple attached demo that seems to work fine, however I have found that with complex vellum sims you really need to run over the "ConstraintGeometry" data as well.

 

vallum_x_constraint.hip

Hi Karl, I hope you don't mind me asking about this ancient thread, I downloaded your example file, but I can't see where exactly you set the Y point values? I see the two SOP solvers in the DOP network, but where in the sop Solvers are you setting the values? Incidentally, I am brand new to Houdini...so.. thank you in advance for your patient..ha!